local ScreenScaler = {}

function ScreenScaler:hideBorders()
	local r, g, b, a = love.graphics.getColor()
	love.graphics.setColor(love.graphics.getBackgroundColor())
	local w, h = love.graphics.getDimensions()

	if self.offset_x ~= 0 then
		love.graphics.rectangle("fill", 0, 0, self.offset_x, h)
		love.graphics.rectangle("fill", w-self.offset_x, 0, self.offset_x, h)
	end

	if self.offset_y ~= 0 then
		love.graphics.rectangle("fill", 0, 0, w, self.offset_y)
		love.graphics.rectangle("fill", 0, h-self.offset_y, w, self.offset_y)
	end

	love.graphics.setColor(r, g, b, a)
end

function ScreenScaler:getPosition(x, y)
		return (x - self.offset_x) / self.scale,
					 (y - self.offset_y) / self.scale
end

function ScreenScaler:isInBounds(x, y)
	if self.scale then
		local w, h = love.graphics.getDimensions()
		return x >= self.offset_x and
					 x < w-self.offset_x and
					 y >= self.offset_y and
					 y < h-self.offset_y
	else
		return true
	end
end

function ScreenScaler:getMousePosition()
	if self.scale then
		return self:getPosition(love.mouse.getPosition())
	else
		return love.mouse.getPosition()
	end
end

function ScreenScaler:getDimensions()
	if self.current_width and self.current_height then
		return self.current_width, self.current_height
	else
		return love.graphics.getDimensions()
	end
end

function ScreenScaler:overrideScaling(width, height)
	local sw, sh = love.graphics.getDimensions()
	self.scale = math.min(sw / width, sh / height)
	self.offset_x = (sw - width * self.scale)/2
	self.offset_y = (sh - height * self.scale)/2
	self.current_width = width
	self.current_height = height
end

function ScreenScaler:start(p1, p2)
	local width, height
	if type(p1) == "number" and type(p2) == "number" then
		width, height = p1, p2
		self.canvas = nil
	elseif p1:typeOf("Canvas") then
		self.canvas = p1
		width, height = self.canvas:getDimensions()
	else
		return
	end

	local sw, sh = love.graphics.getDimensions()
	self.current_width = width
	self.current_height = height
	self.scale = math.min(sw / width, sh / height)
	self.offset_x = (sw - width * self.scale)/2
	self.offset_y = (sh - height * self.scale)/2
	self.active = true

	love.graphics.push()
	if self.canvas then
		love.graphics.setCanvas(self.canvas)
		love.graphics.clear()
	else
		love.graphics.translate(self.offset_x, self.offset_y)
		love.graphics.scale(self.scale)
	end
end

function ScreenScaler:finish()
	love.graphics.pop()
	if self.canvas then
		love.graphics.setCanvas()
		love.graphics.setColor(1, 1, 1)
		love.graphics.draw(self.canvas, self.offset_x, self.offset_y, 0, self.scale)
	else
		self:hideBorders()
	end
	self.canvas = nil
	self.active = false
end

return ScreenScaler